1. Field of the Invention
This invention relates generally to improvements in oil and gas well stimulation, and, more particularly, but not by way of limitation, to improvements in stimulation of oil and gas wells by means of hydra-jet treatment.
2. Description of the Prior Art
The employment of the hydra-jet technique for perforating cased holes, cutting slots or windows in casing and beyond in the formation, cutting pipe for removal, removing cement and debris from casing or open hole, underreaming, formation washing and removal of scale and debris from old perforations is well known in the oil and gas industry. To perform the various processes mentioned above, a great number of hydra-jet tools have been developed for use in the industry. These tools generally employ a jet treating head having one or more nozzles formed therein communicating between the exterior and interior of the jet treating heads. These jet treating heads are secured to the lower end portion of a rigid tubing string which supports the jet treating head adjacent the area to be treated and provides communication between the jet treating head and the ground surface through which pressurized treating fluid is pumped. Various fluids are employed in hydra-jet servicing such as abrasive laden liquids, acids and other chemical solutions adapted to the specific well servicing job being performed.
The known hydra-jet tools and methods have been shown to be somewhat deficient when treating, or attempting to treat, producing formations which have been fractured by explosive and acidized thereby creating an extended stand-off distance from the axis of the well bore to the face of the formation which is to be perforated, cut, acidized or otherwise treated by means of hydra-jet equipment.
The problem of extended stand-off distance is aggravated by the relatively small diameter of the casing in many older wells coupled with the centralization imparted by both the rigidity of the tubing string and the centralizer placed on the tubing string and near the prior art hydra-jet treating tools thereby restricting the positioning of the jet treating tool at a more effective reduced stand-off distance in cased holes, and more specifically, in shot cased holes and acidized or shot open holes.
It is the overcoming of the extended stand-off distance encountered in hydra-jet stimulation of older, previously acidized or shot cased or open holes which has created the requirement for the present invention which provides an economical and reliable solution to the problem of reducing the extended stand-off distance between a hydra-jet treating tool and the face of a formation requiring hydra-jet treatment service.